Lanark, IL Weather & Growing Conditions
This Afternoon
75°F
Showers And Thunderstorms Likely
Showers and thunderstorms likely. Mostly cloudy. High near 75, with temperatures falling to around 72 in the afternoon. Southeast wind around 5 mph. Chance of precipitation is 70%.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| This Afternoon | 75°F | Showers And Thunderstorms Likely | 5 mph SE | 67% |
| Tonight | 62°F | Showers And Thunderstorms | 0 to 10 mph E | 92% |
| Sunday | 66°F | Patchy Fog | 15 mph NE | 60% |
| Sunday Night | 55°F | Chance Rain Showers | 15 mph NE | 34% |
| Monday | 63°F | Chance Rain Showers | 15 mph NE | 49% |
| Monday Night | 50°F | Rain Showers Likely | 15 mph NE | 56% |
| Tuesday | 61°F | Chance Rain Showers | 15 mph NE | 53% |
| Tuesday Night | 48°F | Partly Cloudy | 5 to 15 mph NE | 13% |
| Wednesday | 64°F | Partly Sunny | 10 mph NE | 5% |
| Wednesday Night | 50°F | Mostly Cloudy | 5 to 10 mph NE | 1% |
| Thursday | 66°F | Partly Sunny | 5 mph NE | 7% |
| Thursday Night | 53°F | Mostly Cloudy | 0 to 5 mph NE | 10% |
| Friday | 69°F | Partly Sunny | 0 to 5 mph NE | 6% |
| Friday Night | 52°F | Partly Cloudy | 0 to 5 mph NE | 6% |
Forecast source: National Weather Service (api.weather.gov). Updated through the day.
Growing snapshot for Lanark, IL
Last spring frost
May 2
First fall frost
Oct 7
Growing season
154 days
Hardiness zone
5a
Explore more for Lanark, IL: full frost dates · planting calendar · Illinois frost dates
Climate data from the nearest NOAA station, Mt Carroll, Il (8.8 mi). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 20, 2026.